Trying to copy (drag and drop) an ISO file from SSD1/MacOS Extended to SSD2/FAT32 (two physically different and internal SATA drives):

  • ISO file size: 4.7 GB
  • Space available on SSD2 partition: 20 GB

Error message:

"The item "*.iso" can't be copied because it is too large for the volume's format"

Tried to copy on a USB memory stick (10 GB available): same message.

From the command line:

cp /Users/me/file.iso /Volumes/Untitled/  
cp: /Volumes/Untitled/file.iso: File too large

Copying on the USB stick, same error but after trying for ten minutes (i.e. it thought the space was available, but it was not).

Everything works when coping a smaller file (40 MB).

What is wrong? I have the impression that the issue is not related to the space available on the destination drive, but to the size of the file being copied.

System details:

  • MacBook Pro 17" 2009
  • OSX El Capitan 10.11.6 (the latest one I can use)
  • Long-term, I'd use ExFAT for cross-platform storage. It doesn't have the 4GB file-size limit & can be read & written by Mac & Win natively.
    – Tetsujin
    Dec 27, 2017 at 15:44

1 Answer 1


FAT32 has a maximum size for any individual file: 4 GB.

You can split the file into <4 GB segments, copy to the FAT32 disk, then recombine them once you've copied them off the FAT32 disk to somewhere else.

# make 4 GB file segments
truncate -s 7.8G /path/to/file
split --bytes=3.9GB --numeric-suffixes /path/to/file /path/to/file.part
# copy to disk
cp /path/to/file.part* /Volumes/yourFATdisk/
# copy from disk
cp /Volumes/yourFATdisk/file.part* /path/to/
# combine segments
cat /path/to/file.part* > /path/to/file

Adapted from https://superuser.com/questions/440509/getting-around-the-fat32-4gb-file-size-limit

  • For future readers, please note that AFAIK, the truncate command is for creating a new file. If you already have a big file in mind, don't do it – you'll lose everything that got truncated, which may corrupt the file!
    – SilverWolf
    Dec 27, 2017 at 21:39

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